This article presents an implantable impulse-radio ultra-wideband (IR-UWB) wireless telemetry system for intracortical neural sensing interfaces. A 3-D hybrid impulse modulation that comprises phase shift keying (PSK), pulse position modulation (PPM), and pulse amplitude modulation (PAM) is proposed to increase modulation order without significantly increasing the demodulation requirement, thus leading to a high data rate of 1.66 Gbps and an increased air-transmission range. Operating in a 6–9-GHz UWB band, the presented transmitter (TX) supports the proposed hybrid modulation with a high energy efficiency of 5.8 pJ/bit and modulation quality [error vector magnitude (EVM) < −21 dB]. A low-noise injection-locked ring oscillator (ILRO) supports 8-PSK with a phase error of 2.6°. A calibration-free delay generator realizes a 4-PPM with only $115~\mu \text{W}$ and avoids potential cross-modulation between PPM and PSK. A switch-cap power amplifier (PA) with asynchronous pulse-shaping performs 4-PAM with high energy efficiency and linearity. The TX is implemented in 28-nm CMOS technology, occupying a 0.155 mm2 core area. The wireless module including a printed monopole antenna has a module area of only 1.05 cm2. The TX consumes in total 9.7 mW when transmitting −41.3-dBm/MHz output power. The wireless telemetry module has been validated ex-vivo with a 15-mm multi-layer porcine tissue, and achieves a communication (air) distance up to 15 cm, leading to at least $16\times $ improvement in distance-moralized energy efficiency of 45 pJ/bit/m compared to a state-of-the-art.

This paper presents a millimeter-scale crystal-less wireless transceiver for volume-constrained insertable pills. Operating in the 402-405 MHz medical implant communication service (MICS) band, the phase-tracking receiver-based over-the-air carrier recovery has a ± 160 ppm coverage. A fully integrated adaptive antenna impedance matching solution is proposed to calibrate the antenna impedance variation inside the body. A tunable matching network (TMN) with single inductor performs impedance matching for both transmitter (TX) and receiver (RX) and TX/RX mode switching. To dynamically calibrate the antenna impedance variation over different locations and diet conditions, a loop-back power detector using self-mixing is adopted, which expands the power contour up to 4.8 VSWR. The transceiver is implemented in a 40-nm CMOS technology, occupying 2 mm 2 die area. The transceiver chip and a miniature antenna are integrated in a 3.5 x 15 mm 2 area prototype wireless module. It has a receiver sensitivity of-90 dBm at 200 kbps data rate and delivers up to-25 dBm EIRP in the wireless measurement with a liquid phantom.

The gastro-intestinal (GI) tract is a very important part of the human digestive system but remains largely inaccessible for unobtrusive monitoring. Ingestible electronic devices are a very interesting concept to address this need. This paper discusses the current state of ingestible electronic devices and explores the potential they hold to provide unprecedented insight by measuring several aspects of the complex bio-chemical processes that happen in the GI tract in real-time. This will require novel sensor technology capable of measuring relevant markers with adequate specificity and accuracy. In order to be able to scale this functionality down to a form factor of an easily digestible pill, ultra-low-power wireless interface electronics are needed. This poses certain challenges and innovation opportunities related to sensing, wireless communication and powering to enable the next generation of ingestible electronic devices. [2020-0164]

A 0.8-V Bluetooth 5 (BT5) digitally intensive transceiver with a phase-tracking RX and a digital TX in 40-nm CMOS is presented. For the phase-tracking RX, a hybrid loop filter with a loop-delay compensation is proposed to suppress digitally controlled oscillator (DCO) sidelobe energy, enhancing interference resilience. To facilitate the DCO-based phase-tracking RX for the reception of BT5 signals, a corresponding digital baseband is implemented with a carrier frequency offset (CFO) calibration to remove the initial static CFO error during the preamble, while an automatic frequency calibration tackles the frequency drift during the payload. An all-digital phase-locked loop (ADPLL)-based digital frequency-modulation (FM) interface shared between TX and RX provides a precise deviation frequency control, ensuring the quality of signal transmission and reception. In the RX mode, the chip consumes 2.3 mW from a 0.8-V supply, achieving a figure of merit (FoM) of 180 dB with -91-/-94-dBm sensitivity at 2/1 Mb/s. In the TX mode, it consumes 6.1 mW when delivering a maximum 1.8-dBm output power, resulting in 25% TX system efficiency.

A digital-impulse galvanic coupling as a new high-speed trans-dural (from cortex to the skull) data transmission method has been presented in this article. The proposed wireless telemetry replaces the tethered wires connected in between implants on the cortex and above the skull, allowing the brain implant to be “free-floating” for minimizing brain tissue damage. Such trans-dural wireless telemetry must have a wide channel bandwidth for high-speed data transfer and a small form factor for minimum invasiveness. To investigate the propagation property of the channel, a finite-element model is developed, and a channel characterization based on a liquid phantom and porcine tissue is performed. The results show that the trans-dural channel has a wide frequency response of up to 250 MHz. Propagation loss due to micromotion and misalignments is also investigated in this work. The result indicates that the proposed transmission method is relatively insensitive to misalignment. It has approximately 1-dB extra loss when there is a horizontal misalignment of 1 mm. A pulse-based transmitter application-specific integrated circuit (ASIC) and a miniature printed circuit board (PCB) module are designed and validated ex vivo with a 10-mm-thick porcine tissue. This work demonstrates a high-speed and miniature in-body galvanic-coupled pulse-based communication with a data rate up to 250 Mb/s with an energy efficiency of 2 pJ/bit and has a small module area of only 26 mm2.

A low-power impedance detection method using a hybrid transformer and its analysis are presented. A balun is reused for the hybrid transformer to achieve area-efficiency. The complex impedance detection enables faster optimization on a tunable matching network and its calibration technique increases the detection accuracy. The proposed impedance detection method fabricated in a 40-nm CMOS process consumes only 0.83 mW and demonstrates the accuracy of less than 18° and 0.1 on the Γ detection up to Γ _Ant of 0.5 in ISM2.4 GHz band. After single-step matching network tuning, PA power and RX noise figure are improved by up to 1.2 dB and 1.3 dB, respectively.